Scope and Contents The log covers the period from 13 November 1763 - 15 August 1764, and includes observations of stars and planets and errors and adjustments to instruments and clocks. It mentions the arrival of John Harrison and his chronometers on board HMS 'Tartar' on 13 May 1764 [RGO 4/323: 15v], and includes ratings for these chronometers [RGO 4/323: 15v-16v]. The log also includes details of how and when the astronomer conveyed copies of his observations to Sir Philip Stephens, using different ships...

Scope and Contents

The observations include mathematical equations and methods for finding the inclination of the ecliptic to the horizon [RGO 4/321: 1v-2v]; details of how the observations were taken and with what instruments [RGO 4/321: 3r]; and a log of the observations covering the period 20 September-18 October 1763 [RGO 4/321: 3r-7r]. For a log of the observations of 19 October-8 November, see [RGO 4/321: 38v-40v].

Scope and Contents

The undated draft letter concerns the eclipses of Jupiter's satellites and the deduction of longitude from observations made on board HMS Princess Louisa during a voyage to Barbados. Maskelyne mentions his inability to make these observations from either of Christopher Irwin's marine chairs, which he had been asked by the Commissioners of the Board of Longitude to use and give an opinion on. On the reverse are observations made by Maskelyne whilst in Barbados.

Scope and Contents The journal covers the period 23 February-7 November 1763 and consists of daily tabulated log entries showing the course of the ship and meteorological conditions on the voyage.A set of additional pages is loosely inserted [RGO 4/321: 14-20], showing a sketch of an unnamed island, possibly Barbados [RGO 4/321: 14], and various computations [RGO 4/321: 15-20] including comparisons of observations from voyages of 1761-1764 to ascertain errors in the quadrant [RGO 4/321: 15]; observations...

Scope and Contents

These include observations and computations for the longitude made on or before 2 November, a summary with comments on errors and alterations to instruments, and bearings for landmarks in Barbados (loosely inserted in the volume) [RGO 4/321: 54].